Targeted drug and gene delivery is one of the most rapidly emerging applications for ultrasound contrast agents because it has the potential of reducing the deleterious side effects of the drug to the healthy tissue while minimizing the overall dose needed. Development of new therapeutic contrast agents requires a good understanding of the shell material property effect on the microbubble dynamics and the mechanism of shell breakup. A novel numerical code to investigate the non-spherical dynamics of therapeutic contrast agents under ultrasonic acoustic waves. This model will allow to accurately predict the dynamics behavior of a highly viscous liquid shell used to produce prototype therapeutic contrast agents. Success in modeling the viscous liquid shell in Phase I will build up the foundation for Phase II study for considering multiple agents interaction and viscoelastic liquid shells. This model will also allow simulation of complicated boundary geometries and non-spherical deformations due to interaction between the contrast agent and any surrounding objects. The model will be confronted to controlled laboratory tests of the effect of pressure waves on encapsulated bubbles and on the interaction between oscillating bubbles and the encapsulated agents. In Phase II, the model can be extended to continue beyond shell break up and fragmentation and will address a cloud of contrast agents. [unreadable] [unreadable] [unreadable]